Electronic health records (EHRs) are rapidly being deployed across the U.S., but it is uncertain to what extent they will result in desired benefits with respect to safety or quality of patient care. In addition, hospitals have many degrees of freedom in implementation of EHRs, especially with respect to what decision support they implement. To address these issues, we collaborated to build the Leapfrog CPOE/EHR tool, which evaluates the safety performance of EHRs after deployment, with a particular focus on high impact patient safety and medication safety problems. It is essentially a flight simulator fr EHRs with CPOE, in that hospitals download simulated patients, and then attempt to enter simulated predefined groups of orders, and record whether critical decision support appears in response to these scenarios. The simulated orders used in the test include orders that have actually killed patients in the U.S. as well as many that have caused actual harm to patients. After taking the test, hospitals get immediate feedback on their performance in high impact high prevalence safety areas, and for the subset of potentially fatal orders in the test, hospitals are given the actual list so that they can put key decision support in place. In 2013, more than 800 hospitals in the United States used this tool to self-assess their operational EHR systems for safety performance. Key findings to date have been that there is great variability in how hospitals score with this tool, which is largely independent of vendor-but that hospitals appear to improve their performance over time after taking the test on repeated occasions, for both potentially fatal and non-fatal orders. In this work, we will begin by refining and further developing the Leapfrog CPOE/EHR test using the existing web based testing approach. We will update the inpatient version of the test, so that the test is compatible with the latest versins of the leading EHR vendor products and the latest hospital formularies. In addition a new database will be created to host and administer the test. Thereafter, we will proceed along two tracks, one in which we will work with four study hospitals to refine the test further; all of thes are large hospitals which currently use four different leading major vendor applications. In the second, we will track how many hospitals nationally are using the system, how they perform on the test, and also the extent to which they improve with time. We will have the following three Specific Aims: Aim 1: To measure the national progress on test performance by hospitals in inpatient EHRs in key domains, both in a cohort of hospitals which has taken the test serially, and then in hospitals overall. Aim 2: To work to ensure that inpatient EHRs improve safety by updating a widely used existing test. Aim 3: To improve the test in four test sites to cover additional new high impact safety clinical domains refine them in four health systems, representing four of the leading EHR vendors, and then release them for national use through the Leapfrog Group.